• 한국정밀공학회지
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• 제5권3호
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• pp.81-90
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• 1988

In recent, the requirement of remote control of hychaulic system is in- creasing. The actuator unit whose output position is proportional to input electrical signal needs a pressure reducer and a dump valve. The pressure reducer provides a constant regulated pressure and filters contaminants. The dump valve supplies proper pressure to the pressure reducer and unloads when the system is not operated. In this thesis, dump valve and pressure reducer with auxiliary function are studied. The choke in the pressure reducer prevents actuator from supplying higher pressure than necessary pressure at beginning, and the spring constant affects on the dynamic characterisics. In dump valve, it is proved that diameter of servo-slide hold and choke diameter of dump plunger affects on damping response.

• 동력기계공학회지
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• 제20권1호
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• pp.5-10
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• 2016

Swing check valve is opened when the flow direction is forward, when the flow is reversed, the valve is automatically closed by back pressure. In this study, the internal flow field analysis of the valve was conducted by Fluent. The working fluid used in the study, using liquefied methane $-165^{\circ}C$ (CH4) and velocity field, pressure field, pressure drop coefficient were simulated by varying separately the opening divergence into four intervals from 0 to 100%. The approximate research result are as follow : When the opening divergence is smaller, it appears high pressure on the upstream side, this value is relaxed when the opening divergence is large. Flow rate coefficient of the valve shows a larger value as the degree of opening becomes larger, confirming that the check valve used in the study is in the effective flow rate counting range.

• 한국화재소방학회논문지
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• 제16권4호
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• pp.59-64
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• 2002

버터플라이 밸브의 압력손실과 캐비테이션에 대한 유동특성 연구를 수행하였다. 밸브의 열림각에 대한 압력손실계수는 Carnot 방정식을 응용하여 수식화하였다. 캐비테이션(캐비테이션의 발단, 슈퍼 캐비테이션, 캐비테이션 손상, 초킹 캐비테이션과 같은)은 밸브의 압력손실계수로부터 예측되었다. 압력손실과 캐비테이션 예측은 밸브의 열림각에 대한 두께 비의 변화에 따라 수행하였다. 예측 데이터는 버터플라이 밸브를 개발하는데 필요한 엔지니어링 데이터로 활용하고자 한다.

• 한국기계가공학회지
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• 제14권5호
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• pp.42-49
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• 2015

In this study, the multi-disk of a high-pressure drop control valve is designed and manufactured. Then, the flow rate and high-pressure drop of fluids flowing in the high-pressure drop control valve is CAE/CFD. This study involves numerical analysis for the Zambil offshore project of a high-pressure drop control valve. ANSYS used a solver for offshore structures analysis. A high-pressure drop control valve, which transforms the power transfer of a system by reducing the inlet pressure of 345bar to the outlet pressure of 112bar, is a fundamental component in the offshore process. This study not only analyzes the relation between pressure drop and fluid velocity in a trim by using fluid analysis, but also examines the possibility of cavitation in a valve in addition to the plot for the extension of lifespan. It is demonstrated that the pressure drop from 345bar to 112bar is more feasible in the presence of the trim, which can induce a continuous and diminutive pressure drop in order to prevent cavitation in a high-pressure drop control valve.

• Korean Journal of Acupuncture
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• 제38권4호
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• pp.308-316
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• 2021

Objectives : This study aimed to develop a cupping pressure control valve for limiting maximum negative pressure while achieving clinical therapeutic outcomes to minimize side effects induced by excessive negative pressure of air extraction cupping devices. Methods : To determine the clinical necessity and suitability of the cupping pressure control valve, this study was designed to measure the change in pressure with or without the valve using both a manual and an electric suction pump. Results : While the maximum pressure was limited by the pressure control valve, the pressure did not increase above a certain level regardless of the type of manual or electric pump. Conclusions : This study will contribute to the development of a safer and more effective base technology for cupping treatment in oriental medicine.

• 대한기계학회논문집A
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• 제26권8호
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• pp.1552-1564
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• 2002

Meter-in, meter-out and bleed-off circuits are widely utilized in order to adjust the speed of a hydraulic actuator by using a flow control valve and in order to regulate the pressure of a hydraulic volume by using a simple on-off valve. In these circuits, a relief valve serves either to maintain constant system pressure or to protect the system from over-pressure loading. The relief valve of a bleed-off circuit is the second case frequently undergoing on-off action during operation. It makes the analysis of the pressure control characteristics of the circuit highly difficult. In this paper, steady-state flow rate, pressure, heat loss and efficiency of the three circuits are reexamined and basic experiments far obtaining the characteristics of a pump and relief valve are conducted. Finally, simple empirical first-order dynamic models of decreasing and increasing pressure were separately proposed and verified by comparison with experiment. As the result, the basis for the theoretical analysis of the pressure control characteristics of a bleed-off circuit using a simple on-off valve is established.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1581-1584
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• 2007

The safety valve is the important equipment used to protect the pressure vessel and pressure facilities from overpressure by discharging the operation medium when the pressure of system is reaching the design pressure of the system. Some materials for a safety valve disk are studied in this paper. A studied safety valve has to resist sulfurous acid and nitric acid. etc. Furthermore teflon which is a general material of the valve easily sticks to a disk and a sliding part of the valve by thermal expansion. Therefore both teflon and stainless-steel are used to improve these problems. The analysis of the thermal expansion is conducted with commercial FEM software to improve the problems. Boundary conditions were temperature and load in this study. From the analysis, the thermal expansion of by teflon/stainless steel-made valve is lower than that of teflon-made valve under high temperature. Thus, teflon/stainless steel-made valve is safe and no malfunction by thermal expansion.

• 한국산업융합학회 논문집
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• 제26권3호
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• pp.381-387
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• 2023

This study conducts the flow analysis on the basis of the impeller RPM of water measuring valve and differential pressure at valve inlet and outlet. The software used for the flow analysis is STAR-CCM+. In terms of the structure of the measuring valve, it has an impeller installed inside, and a metering chamber has inlet and outlet holes. The flow analysis on the water measuring valve drew the following conclusions: The flow rate and flow coefficient distribution according to the impeller RPM and differential pressure were on the linear increase. Regarding the flow field in the valve, the increased differential pressure had the highest velocity distribution, and complex flow field was generated in the measuring chamber. In particular, since the path between the inlet and outlet holes in the measuring chamber and the valve body was narrow, there was a section that had flow field interference. Given that, it showed the feature of the valve used for water measuring on the basis of the impeller RPM.

• 한국자동차공학회논문집
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• 제9권5호
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• pp.179-187
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• 2001

In this paper, a primary pressure regulating type ratio control system is developed for a metal belt CVT, and the CVT ratio changing characteristics are investigated by simulation and experiment. The hydraulic part of the ratio control system has a simple structure with one 3-way spool valve as a main ratio control valve and one bleed type variable force solenoid as a pilot valve. The mathematical modelling of the CVT hydraulic system is derived by considering the CVT shift dynamics. Simulation results of CVT speed ratio and the primary pressure agree with the experimental results demonstrating the validity of the dynamic models. It is found from the simulation and experimental results that the response time of speed ratio and primary pressure can be shortened by increasing the ratio control valve port area, and the size of feedback orifice of ratio control valve gives a damping effect on the primary pressure oscillation.

• 한국공작기계학회논문집
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• 제12권6호
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• pp.29-35
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• 2003

In this research 4 plate type ER-Valves which have same surface but different width and length are designed and an experimental apparatus is constructed. With this experimental apparatus, flow rate and pressure drop of ER fluid flowing in ER-valves are measured with varying electric field strength of ER-valve, and relation between valve types and pressure drop is also experimented. ER fluid is made silicon oil mixed with 40wt% starch having hydrous particles. If we allow the same electric field in the ER-Valve, we came to how that the pressure drop is effected by the electrode length and electrode width. When the strength of the electric field increased, the pressure drop happened big and the flow rate decreased.